Swivel chair



FIG. 1 is a perspective view of a swivel chair showing the new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof; and,

FIG. 6 is a top view thereof.

The broken lines shown in the drawings illustrate portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for a swivel chair, as shown and described. 